Many resources are available online to research your family tree. Here are a few which contain extensive links to those resources:Yahoo!'s Genealogy Links Page - Yahoo! is categorized by subject and provides a searchable database of each or all indexed material. A good starting point when you are looking for anything on the Internet.
The Genealogy Homepage - Stephan A. Wood's comprehensive (1600+ links) site.
NARA Archival Informational Locator (NAIL) - The National Archives and Records Administration maintains a searchable database of textual records, still pictures, sound records, maps, charts, films and videos.
Ellis Island - Searchable database of passenger records for ancestors who came through Ellis Island in New York to the U.S. from 1892 to 1924.